Encasement for heat transfer fluid (htf) conduits

ABSTRACT

An encasement for heat transfer fluid (HTF) conduits having an outer layer ( 1 ) of sheet metal and an intermediate layer ( 2 ) below the outer layer ( 1 ). The intermediate layer ( 2 ) is made of insulating material having a maximum thickness of 1.4 inches (35 mm). The heat transfer fluid (HTF) conduits are movable.

This application claims benefit of Serial No. 201131163, filed 8 Jul.2011 in Spain and which application is incorporated herein by reference.To the extent appropriate, a claim of priority is made to the abovedisclosed application.

FIELD OF THE INVENTION

The invention relates to an insulation and encasement system for movableheat transfer fluid (HTF) conduits.

BACKGROUND OF THE INVENTION

Removable mat-based insulations made up of the following materials areknown:

1. A glass fiber fabric with a stainless steel foil or sheet on itsouter face as the encasement of the inner face.

2. A 1 inch (25 mm) thick ceramic fiber insulation layer with a densityof 8 lb/ft³ (128 kg/m³) as inner insulation.

3. A glass fiber fabric coated with silicone or Teflon as the encasementof the outer face (depending on the engineering).

4. These mats were sewn at all their ends by a glass fiber wireresistant to high temperatures.

Theoretically, these specified mats met some of the requirements thatwere specified, and they did not meet others but it was considered theonly solution. These requirements were the following:

A. In the event of a thermal oil leak in the attachments between pipesegments in the swivel arms, which were already provided for, the oilcould not impregnate the insulation whereby the outer face of theencasement of the inner face of the mat could not let the oil passthrough to the mats covering the three ball joints of each arm. This wasachieved with the glass fiber fabric with the stainless foil because thestainless acted as a barrier for the oil.

B. The insulation in the rotating ball joints had to be easily removablefor frequent required maintenance to graphitize the ball joints. Thiswas achieved by making independent mats for the ball joints.

C. The outer encasement of the mat had to be impermeable to prevent theinsulation from getting wet because this would cancel out the insulatingeffect and would furthermore progressively deteriorate it. This wasachieved with the silicon or Teflon fabric.

D. The arm had to be perfectly insulated and, like the rest of thepipes, had to have minimal heat losses. This was not achieved becausethe 1 inch (25 mm) layer of ceramic fiber achieves only a 23-29%insulating power with respect to the 100 mm thick mat of 6.7 lb/ft³ (100kg/m³), which is the material and thickness used for insulating pipes upto 3″ in diameter conducting HTF in the solar field because the lambdavalues thereof at 752° F. (400° C.) are very similar. Thicker ceramicfiber could not be installed because the pipe of the arms is 2″ or 2.5″in diameter and it is impossible to manufacture mats for the elbows andfor the ball joints such that they correctly close and absorb, withoutleaving ball joints, the movements of the arm. It was considered thatthere was not a better solution and the mats were installed.

E. The insulation-encasement system installed had to absorb themovements of the swivel arm, in all its directions, without causing theinsulation to slide, the encasement to deteriorate and, accordingly,without forming ball joints through which heat losses occur and watercan enter. Since the mats are installed in new condition, they meet thisrequirement, but experience in several plants has demonstrated thatsince they are mats which are tied with wire or with glass fiber fabricstrips, with the continuous arm movement and the action of atmosphericagents, sliding takes place and ball joints are formed, all of whichcompletely deteriorate the quality of the insulation.

After about 7-12 months of the mats being installed in the Spanishplants, several problems were detected and, when communicating with theAmerican plants, it was corroborated that new problems had arisen thatwere not foreseen during the design stage and that the mats furthermoredid not meet these requirements. These problems were the following:

F. The ray of sunlight reflected by the mirrors on the pipe is reflectednot only frontally towards the pipe conducting the HTF but it is alsoreflected laterally, and depending on the time of day or season of theyear, there are concentrations of solar radiation on the mats of up to 7BTU/ft² (80 kW/m²). This means that the silicone or Teflon is withstoodat very high temperatures, the engineering firms estimate that between662° and 842° F. (350° and 450° C.), and after 284°-356° F. (140-180°C.), at the most, these materials disintegrate causing the glass fiber,which allows the entrance of water, to gradually wizen and the mats openup and end up breaking and falling.

G. In two of the Spanish plants, there were HTF leaks in ball joints,leading to ignition and causing considerable fires in the area of theball joint. After investigating the causes of this ignition, when theinsulating materials and the stainless foil are fire-resistant, it wasconcluded that it was because the thermal oil at 752° F. (400° C.) underthe pressure at which the fluid is conducted and in contact with oxygencan cause ignition if that pressure is contained within the mat and doesnot find an escape route. With the mats this pressure has no escaperoute, so the risk of ignition of the HTF is highly probable. The firesoccurring in the Spanish plants in the ball joints were one of thebiggest engineering problems because the environmental hazard is veryconsiderable if the fire spreads.

H. The swivel arms are supported in most engineering designs by frameswith rotating tubes acting as bearings so that the arms move throughthose bearings. Since the ceramic fiber-insulated mats lack rigidity,they gradually crush the insulating material, breaking it and moving itto the sides, whereby finally the area of the mats moving through thesupports virtually ends up with no insulation with the subsequentlosses.

The mats have been deteriorating little by little in all the facilitiesand a patch has been made in most consisting of deflecting collarsplaced above the mats and preventing the solar concentration thereon.This solution has two drawbacks, the first being that it makes thesolution considerably more expensive, and the second being that thesedeflectors have a sail effect and distort the calculated movement of themirrors, whereby being able to result in breakdowns in the rotatingmechanisms.

SUMMARY OF THE INVENTION

The invention relates to a system solving all the problems indicatedabove by means of the following constructive solutions:

A. Need to prevent the passage of thermal oil to the insulation in theevent of a leak in the ball joint. The ball joint is insulated by meansof placing slots on the outer face and side faces of the aluminum sheetmetal which internally contains the heat insulation, and the inner faceof the insulation is covered with a glass fiber fabric with 2 inch (50μm) stainless steel foil which prevents impregnation of the insulationin the event of a leak. The attachments of the fabric with the sheetmetal are finished with a mastic resistant to 1832° F. (1,000° C.).

B. Need for the insulation of the ball joints to be easily removable.The three ball joints of each arm are insulated and encased by means ofplacing slots in aluminum made in two halves which are fitted to oneanother and closed with 4 clamp-like quick closures, whereby anyunskilled operator can assemble and disassemble the box without anyproblem for maintenance tasks.

C. Need for the outer encasement of the mat to be impermeable to preventthe insulation from getting wet. With the solution of the presentinvention, all the insulation of the swivel arm has an encasement ofaluminum sheet metal 0.02 and 0.06 inch (0.5 mm and 1.5 mm) thick and isimpermeable to water.

D. Need for the heat losses occurring in the swivel arms to be equal orvery close to that of the remaining pipes. All the straight segments,elbows and rotating ball joints are insulated with preformed segments ofmicroporous microtherm MPS material 1 inch (25 mm) thick. Themicroporous microtherm material has an excellent lambda value andachieves the losses per linear meter of 2″ (50.8 mm) pipe to bevirtually the same. The heat losses occurring with ceramicfiber-insulated mats are reduced by more than 60% with this material.

E. Need for the installed insulation-encasement system to absorb themovements of the swivel arm in all its directions without the insulationsliding, the encasement deteriorating and accordingly there are no balljoints causing heat losses and the entrance of water. In the solutiondeveloped in the present invention, rims 0.4-0.6 inch (10-15 mm) highare made in the final pipe segments, in the elbows, located with theball joint, on which rims the insulation boxes of the ball jointsthemselves are assembled and supported. The insulation box of the balljoint is therefore rendered “floating” or “rotating” because the sidecovers of this box are made with an exact measurement so that theycannot pass over the rims. At the ends of insulation of the pipe whereit meets up with the ball joint a cover is applied which is made eitherof 0.026 inch (0.6 mm) aluminum sheet metal or of glass fiber fabricwith 2 inch (50 μm) stainless foil so that, in the event of an HTF leakin the ball joint, the oil does not pass on to the remaining pipesegments.

F. Need for the encasement material used in the ball joint to withstandthe temperatures reached with the solar concentration caused by theeffect of the side reflection of the mirrors towards the swivel arms.With the solution of the present invention, since the entire coating ofthe insulation is based on aluminum sheet metal the possibility ofdeterioration of the encasement is eliminated because aluminum melts at1112° F. (600° C.). This resistance is proven in the installed plantsand it is also checked in insulation parts protecting parts arranged inthe pipe of the mirrors and continue to be integral several years later.

G. Need to prevent the risk of ignition in the event of an HTF leak inthe ball joints.

With the rotating or floating encasement box for the ball joints, thecoating is never leak-tight, whereby in the event of a leak the releasedpressure will find an outlet along the perimeter of the box which atthat time is open depending on the position of the arm at the time ofthe leak. The mats in all ball joints become displaced by the armmovements and by the assembly and disassembly operations by themaintenance personnel; the consequence is that the mats often becomeinterposed in the union joint of the pipe with the ball joint andmovement restrictions of the arms are generated which can derive inimportant damage to the pipes and the ball joints.

H. Need to prevent insulation from deteriorating and creating large heatbridges caused by friction of the support of the swivel arm or bydisplacement of the mats. With the aluminum encasement of the presentinvention, the sheet metal withstands the friction, the movements andthe blows caused by the change in inclination occurring in the supports.To give a coverage interval to the resistance of the sheet metal, thealuminum sheet metal segment sliding on the support is installed with athickness of 0.06 inch (1.5 mm), thereby assuring the integrity of theinsulation it protects. Given that the ball joints are encased inaluminum boxes, the ball joints are safe from a restriction in movementby an interference of the encasement.

Despite the fact that microtherm insulating material is much moreexpensive than rock wool, the present invention has a lower cost thanwhat the mats entailed because of the development of manufacturing andassembly processes with a high manufacturing and assembly standard.

In addition to all the solutions to the problems that have arisen in theoperation of the swivel arms, the present invention also providessolutions to facilitate the installation of the encasement system.

The installation of the encasement of the invention is not technicallycomplex and does not require being assembled by skilled insulationinstallers (heat insulation installers) so qualified heat insulationinstallers are not needed for installation or for de-installation, whichresults in a lower installation manual labor cost, and especially in theevent of having to remove all the insulation of the swivel arm formaintenance or inspection tasks, the same operator who disassembles itcan assemble it again without difficulty. With the solution of thepresent invention the encasement box of the ball joints and theremaining insulation, straight segments, z-shaped segments and elbows,can be disassembled.

The installation of the invention has a very rapid assembly. This isbecause the segments are supplied with the insulating systempreassembled therein, so the assembly time is very short. Prefabricationin a workshop can start at a very early phase of the project such thatwhen the swivel arms are ready to be insulated, 100% of the encasementsare prefabricated on site for installation. This milestone, in which themechanical fitter supplies the arms to the insulation installer forinsulation, is always uncertain because the pipes have to pass severalpressure tests and treatments and problems often arise with the tests,which causes a delay in the construction job resulting in an overalllengthening of the project, because until the arms are insulated, theHTF cannot be inserted in the heat circuit due to it being able tofreeze if it drops below certain temperatures. In current projects, thisfactor is a drawback because the engineering firms give suppliersincreasingly shorter execution times because this directly results in alower financing cost for the construction of the projects and thereforein the total cost of projects. The reduction of construction costs ofsolar thermal plants is the main objective of investors and engineeringfirms because the viability of the solar thermal energy in the future inthe energetic mix of countries depends on this reduction. Increasingstress is placed on reducing assembly times of all plant items.

These two features are a pending issue for traditional insulationsystems because they always require a qualified assembly and disassemblyand the work hours to be used in assembling them are always a bone ofcontention with project managers.

The present invention comprises an easy-to-assemble insulation kit forthe swivel arms of the solar thermal plants.

The same base insulation and encasement materials are used in this kitas those used in the solution described above with microtherm MPS andaluminum sheet metal, but providing new and innovative pre-assembly andpre-mounting solutions which achieve the two advantages mentioned above:

-   -   The kit can be assembled-disassembled by any general plant        maintenance operator without having to be a skilled heat        insulation installer and requiring no machinery (drills or        riveters) for installation and de-installation, only a manual        screw driver.    -   The kit provides a 75% saving in assembly time in the on-site        assembly, whereby improving the overall profitability of solar        thermal plants. In the case of plants greater than 200 and 350        MW, the savings can be very considerable.

The kit solution is achieved by pre-assembling all the insulation andencasement parts in a workshop, whereby the insulation will be suppliedto the site incorporated in the encasement by means of applying adhesivewith a microtherm-type mastic or the like resistant to 1832° F. (1,000°C.).

The kit will be supplied on site in several parts, both the simple armand the double arm. Three parts are always the encasement boxes of theball joints, whereas the rest are straight segments, z-shaped segmentsand elbows attached in several parts.

In all the parts, the insulation is incorporated in the encasement andthe system is made up of two halves facing one another.

The encasement sheet metal segment ending against the ball joints havethe rim supporting the box of the ball joint. All the remaining endshave a smaller rim for inter-segment assembly.

There are three types of elements for fixing and sealing the arms:

-   -   A metal flange closing and sealing the two metal rims in which        each segment ends.    -   A ball joint sealing all the longitudinal attachments resulting        from the coupling between the two halves. This ball joint has a        lower layer of impermeable material such as Teflon, polyethylene        or another impermeable material and with a heat resistance of        about 392° F. (200° C.), and an aluminum cover protecting this        impermeable layer from the solar concentration reflected by the        mirrors on the arms.    -   Metal flanges with screw locking which fix the entire system and        secure the sealing joints.

BRIEF DESCRIPTION OF THE DRAWINGS

A series of drawings which aid in better understanding the invention andwhich expressly relate to an embodiment of said invention presented as anon-limiting example thereof is very briefly described below.

FIG. 1A shows an encasement of the invention.

FIG. 1B shows an encasement of the invention in kit mode.

FIG. 1B1 shows a detail of the area of contact between a box and anelbow.

FIG. 1B2 shows a detail of the area of attachment between segments wherethe assembly rim is illustrated.

FIG. 2 shows a clamp-type closure.

FIG. 3 shows a double arm.

FIG. 4 shows a single arm.

FIG. 5 is a cross-section showing two halves of an encasement, thelongitudinal joint and a longitudinal flange.

FIG. 6 is a cross-section showing two halves of an encasement, each halfhaving a flange configured to house a longitudinal joint.

FIG. 7 shows a detail of the area of contact between the flange of eachhalf and the longitudinal joint.

DETAILED DESCRIPTION OF AN EMBODIMENT

As illustrated in FIGS. 1A and 1B, an embodiment of the inventionrelates to an encasement for heat transfer fluid (HTF) conduits:

-   -   1a) comprising an outer layer (1) of sheet metal, encasement        layer, configured to protect against working conditions such as        high temperatures and high degree of sunshine;    -   1b) comprising an intermediate layer (2), insulation layer:        -   1b1) below the outer layer (1);        -   1b2) of insulating material having a maximum thickness of            1.4 inch (35 mm);    -   1c) wherein the heat transfer fluid (HTF) conduits are movable.

According to other features of the invention:

-   -   2. The metal is aluminum.    -   3. The sheet metal has a thickness comprised between 0.02 and        0.06 inch (0.5 and 1.5 mm).    -   4. The insulating material is microporous.    -   5. The insulating material configured to heat-insulate has a        heat transfer coefficient comprised between 0.11 and 0.33 BTU        inch/(hr ft²F) (0.016 and 0.048 W/mK) at 752° F. (400° C.) of        temperature of heat transfer fluid (HTF).    -   6. The insulating material is MPS shell.    -   7. As illustrated in FIGS. 1A and 1B, the encasement comprises:    -   7a) an inner layer (3) comprising:        -   7a1) a glass fiber fabric (31) having a thickness comprised            between (0.1 mm and 1.5 mm); 0.004 and 0.06 inch        -   7a2) a sheet (32) made of corrosion resistant material,            which can be stainless steel or aluminum, having a thickness            comprised between 0.004 and 0.06 inch (0.1 mm and 1.5 mm).    -   8. As illustrated in FIGS. 1A and 1B, the encasement comprises:    -   8a) a rim (4):        -   8a1) having a height comprised between 0.4 and 0.6 inch (10            and 15 mm);        -   8a2) configured to define a flange having a coupling            diameter (d) to allow coupling between two consecutive            segments of the encasement.    -   9. As illustrated in FIG. 1B1, the encasement comprises:    -   9a) a cover (51, 531, 532) configured to close a front face of        the encasement;    -   9b) a ceramic fiber washer (6) between the cover (51, 531, 532)        and the rim (4).    -   10. The cover (51, 531, 532) comprises 0.016 and 0.04 inch        (0.4-1 mm) thick aluminum sheet metal (51), as illustrated in        FIG. 1B1.    -   11. As illustrated in FIG. 1B1, the cover (51, 531, 532)        comprises:        -   11a1) a glass fiber fabric (531) having a thickness            comprised between 0.004 and 0.06 inch (0.1 and 1.5 mm);        -   11a2) a sheet (532) made of corrosion resistant material,            which can be stainless steel or aluminum, having a thickness            comprised between 0.04 inch and 0.4 inch (0.1 and 1.5 mm).    -   12. The encasement has a shape selected from straight, elbow,        z-shaped segment, determined by a directrix of the conducting        segment.    -   13. The encasement:    -   13a) is box-shaped having a cylindrical inner cavity, as        illustrated in FIG. 1B, having:        -   13a1) a box diameter (D) greater than a coupling diameter            (d);        -   13a2) a length (L);        -   13a3) the box diameter (D) and the length (L) being            configured to allow clearance between the box and the            adjacent encasement segments. The clearance, which can be            comprised between 1 and 10 mm, allows the box to have a            floating arrangement on the adjacent encasement segments.            Therefore, during the movement of the arms, the boxes can            move over the elbows, straight segments or other segments of            the encasement. Additionally, the clearances also allow            variations in the dimensions of the components of the            invention due to heat loads.    -   14. As illustrated in FIG. 5, the encasement comprises two        halves (1001A, 1001B) configured to envelope a conduit and to        fit with one another.

According to a first embodiment of the invention, two steps arenecessary for assembling the insulation and encasement system. In afirst operation, the insulation layer or intermediate layer (2) isplaced on the conduit, and then in a second operation, the encasementlayer or outer layer (1) is placed on the insulation layer. These twolayers are placed in the field, i.e., it is necessary to perform the twooperations at the location of the facility of the conduits to beprotected.

As illustrated in FIG. 1A, the outer layer (1) of the elbows comprises aplurality of segments for forming the curved segment from the precedingsegment, or incoming segment entering the elbow, to the subsequentsegment, or outgoing segment exiting the elbow.

In a second embodiment of the invention, a kit is previously prepared sothat the operations to be performed in the field are simplified. Withthe second embodiment of the invention, the components of the kit areready to be placed directly and in a single operation on the facility ofthe conduits. The kit supplied for being installed in the field alreadyhas the insulation layer or intermediate layer (2) and the encasementlayer or outer layer (1) integrated in its components. With thisarrangement, the assembly of the insulation and encasement system issimplified as only the components already incorporating the intermediatelayer (2) and the outer layer (1) have to be assembled on the conduits.As illustrated in FIG. 1B, the outer layer (1) of the elbows comprises aright angle shape for forming the change of direction segment from thepreceding segment, or incoming segment entering the elbow, to thesubsequent segment, or outgoing segment exiting the elbow. Therefore, inthe embodiment of the kit the elbows are formed by two halves at a rightangle from the preceding segment, or incoming segment entering theelbow, to the subsequent segment, or outgoing segment exiting the elbow.The number of parts needed for forming an elbow is thus reduced.

-   -   15. The two halves are configured to contact in 2 diametrically        opposed generatrices as illustrated in FIG. 5.    -   16. The encasement illustrated in FIG. 1B2 comprises an assembly        rim (1000) at a front end configured to axially assemble a first        encasement (1001) with a consecutive second encasement (1002).    -   17. The encasement comprises means for fixing and sealing the 2        halves:    -   17a) a circular metal flange (7) as illustrated in FIG. 1B2        configured to close and seal the assembly rims (1000);    -   17b) a joint (1001C) as illustrated in FIG. 5 configured to seal        an attachment between the two halves (1001A, 1001B);    -   17c) perimetric closing means selected from a plurality of        flanges with screw locking and a plurality of clamp-like quick        closures (6) as illustrated in FIG. 2 configured to allow        assembling/disassembling the encasement.    -   17d) The encasement illustrated in FIG. 5 comprises means for        closing the 2 halves comprising:    -   a longitudinal metal flange (1001D) configured to externally        close the two halves (1001A, 1001B).    -   17e) The encasement illustrated in FIGS. 6 and 7 comprises means        for closing the 2 halves comprising:    -   a first longitudinal metal flange (1001E) on a first half        (1001A);    -   a second longitudinal metal flange (1001F) on a second half        (1001B);    -   wherein the joint (1001C) is housed between the first        longitudinal metal flange (1001E) and the second longitudinal        metal flange (1001F).    -   18. Simple swivel arm as illustrated in FIG. 4 comprising:    -   18a) 3 boxes according to features 13)-13a3):        -   18a1) a first entrance box (101);        -   18a2) a second exit box (102);        -   18a3) a third intermediate box (103);    -   18b) 5 elbows according to feature 12:        -   18b1) a first elbow (201) exiting the entrance box (101);        -   18b2) a second elbow (202) entering the intermediate box            (103);        -   18b3) a third elbow (203) exiting the intermediate box            (103);        -   18b4) a fourth elbow (204) entering the exit box (102);        -   18b5) a fifth elbow (205) exiting the exit box (102);    -   18c) 2 straight segments according to feature 12:        -   18c1) a first incoming segment (301) between the entrance            box (101) and the intermediate box (103);        -   18c2) a second outgoing segment (302) between the            intermediate box (103) and the exit box (102).    -   19. Swivel arm configured as illustrated in FIG. 3 comprising:    -   19a) 3 boxes according to features 13)-13a3):        -   19a1) a first entrance box (101);        -   19a2) a second exit box (102);        -   19a3) a third intermediate box (103);    -   19b) 4 elbows according to feature 12:        -   19b1) a first elbow (201A) entering the entrance box (101);        -   19b2) a second elbow (202) entering the intermediate box            (103);        -   19b3) a third elbow (203) exiting the intermediate box            (103);        -   19b4) a fourth elbow (204A) exiting the exit box (102);    -   19c) 2 z-shaped segments according to feature 12:        -   19c1) a first incoming segment (301) between the entrance            box (101) and the intermediate box (103);        -   19c2) a second outgoing segment (302) between the            intermediate box (103) and the exit box (102).

1. An encasement for heat transfer fluid, conduits, comprising: an outer layer of sheet metal; an intermediate layer: below the outer layer; of insulating material having a maximum thickness of 1.4 inches (35 mm); wherein the heat transfer fluid conduits are movable.
 2. The encasement of claim 1, wherein the encasement is box-shaped having a cylindrical inner cavity having: a box diameter greater than a coupling diameter; a length; the box diameter and the length being configured to allow clearance between the box and adjacent encasement segments.
 3. The encasement according to claim 1, comprising an assembly rim at a front end, configured to axially assemble a first encasement with a consecutive second encasement.
 4. The encasement according to claim 3, comprising attachment means comprising: a circular metal flange configured to close and seal assembly rims.
 5. The encasement according to claim 1, comprising two halves configured to envelop a conduit and to fit with one another.
 6. The encasement according to claim 5, wherein the two halves are configured to contact in two diametrically opposed generatrices.
 7. The encasement according to claim 5, comprising means for fixing and sealing the two halves comprising: a joint configured to seal an attachment between the two halves.
 8. The encasement according to claim 5, comprising means for closing the two halves comprising: a longitudinal metal flange configured to close the two halves.
 9. The encasement according to claim 7, comprising means for closing the two halves comprising: a first longitudinal metal flange on a first half; a second longitudinal metal flange on a second half; wherein the joint is housed between the first longitudinal metal flange and the second longitudinal metal flange.
 10. The encasement according to claim 5, comprising means for fixing and sealing the two halves comprising: perimetric closing means configured to allow assembling and disassembling the encasement selected from: a plurality of flanges with screw locking; and a plurality of clamp quick closures configured to allow opening and closing without additional tools.
 11. The encasement according to claim 1, comprising: a rim: having a height between 0.4 and 0.6 inches (10 and 15 mm); configured to define a flange having a coupling diameter to allow coupling between two consecutive segments of the encasement.
 12. The encasement according to claim 11, comprising: a cover configured to close a front face of the encasement; a ceramic fiber washer between the cover and the rim.
 13. The encasement according to claim 12, wherein the cover comprises 0.015-0.04 inches (0.4-1 mm) thick aluminum sheet metal.
 14. The encasement according to claim 11, wherein the cover comprises: a glass fiber fabric having a thickness between 0.004 and 0.06 inches (0.1 and 1.5 mm); a sheet made of corrosion resistant material having a thickness between 0.004 and 0.06 inches (0.1 and 1.5 mm).
 15. The encasement according to claim 1, wherein the metal is aluminum.
 16. The encasement according to claim 1, wherein the sheet metal has a thickness between 0.012 and 0.016 inches (0.3 and 1.5 mm).
 17. The encasement according to claim 1, wherein the insulating material is microporous.
 18. The encasement according to claim 1, wherein the insulating material configured to heat-insulate has a heat transfer coefficient between 0.11 and 0.33 BTUin/(hrft²F) (0.016 and 0.048 W/mK) at 752° F. (400° C.) of temperature of heat transfer fluid.
 19. The encasement according to claim 1, wherein the insulating material is MPS shell.
 20. The encasement according to claim 1, comprising: an inner layer comprising: a glass fiber fabric having a thickness between 0.004 and 0.06 inches (0.1 mm and 1.5 mm); a sheet made of corrosion resistant material having a thickness between 0.004 and 0.06 inches (0.1 mm and 1.5 mm).
 21. The encasement according to claim 1, wherein the casement has a shape selected from a straight, elbow, z-shaped segment, determined by a directrix of the conducting segment.
 22. A simple swivel arm, comprising: three boxes according to claim 2: a first entrance box; a second exit box; a third intermediate box; five elbows according to claim 20: a first elbow exiting the entrance box; a second elbow entering the intermediate box; a third elbow exiting the intermediate box; wherein the boxes have a cylindrical inner cavity having: a box diameter greater than a coupling diameter; a length; the box diameter and the length being configured to allow clearance between the box and adjacent encasement segments; a fourth elbow entering the exit box; a fifth elbow exiting the exit box; two straight segments according to claim 20: a first incoming segment between the entrance box and the intermediate box; a second outgoing segment between the intermediate box and the exit box.
 23. A composite swivel arm, comprising: three boxes: a first entrance box; a second exit box; a third intermediate box; wherein the boxes have a cylindrical inner cavity having: a box diameter greater than a coupling diameter; a length; the box diameter and the length being configured to allow clearance between the box and adjacent encasement segments; four elbows according to claim 20; a first elbow entering the entrance box; a second elbow entering the intermediate box; a third elbow exiting the intermediate box; a fourth elbow exiting the exit box; two z-shaped segments according to claim 20: a first incoming segment between the entrance box and the intermediate box; a second outgoing segment between the intermediate box and the exit box. 